1. Field of the Invention
The present invention is related to a backside-illuminated imaging device that performs imaging by illuminating light from a back side of a semiconductor substrate to generate electric charges in the semiconductor substrate based on the light and reading out the electric charges from a front side of the semiconductor substrate.
2. Description of Related Art
Various kinds of backside-illuminated imaging devices are proposed, each of which performs preformed imaging by illuminating light from a back side of a semiconductor substrate to generate electric charges in the semiconductor substrate based on the light, accumulating the electric charges in the charge accumulating areas formed on a front side of the semiconductor substrate, and output signals in accordance with the electric charges accumulated in the charge accumulating areas to the outside of the device by CCD or CMOS circuit or the like formed on the front side of semiconductor substrate (e.g., JP-A-2005-142221).
Also, JP-A-11-355790 discloses an imaging device in which a first photosensitive element group including photosensitive elements arrayed in a square lattice pattern for detecting luminescent components of light and a second photosensitive element group including photosensitive elements arrayed in a square lattice pattern for detecting hue components of the light are arranged on a silicon substrate in such a manner that the first and second photosensitive element groups are shifted from each other at adjacent positions so as to form a so-called honeycomb array pattern.
The backside-illuminated imaging device disclosed in JP-A-2005-142221 is a CMOS type imaging device. If the backside-illuminated imaging device is a CCD type imaging device, light receiving areas can be made larger since it is not necessary to provide CCD on the back side of the semiconductor substrate. However, if the light receiving areas become large, the distance between the charge accumulating areas located adjacent to each other becomes short. As a result, there are many possibilities that mixed colors may readily occur in peripheral portions of the backside-illuminated imaging device, in which incident angles of light are steep.
When a color filter array capable of realizing the device characteristics disclosed in JP-A-11-355790 is used as a color filter array provided above the backside surface of the semiconductor substrate, there is a probability that at the peripheral portion of the imaging device, light passing through the filter provided above a photosensitive element for detecting a hue component may be entered into a photosensitive element for detecting a luminance component and also light passing through the filter provided above the photosensitive element for detecting a luminance component may be entered into the photosensitive element for detecting a hue component. If light to be originally entered into a photosensitive element enters into its adjoining photosensitive element that is for detecting a luminance component, this is not any major problems, since the sensitivity of the photosensitive element for detecting a luminance component is high. However, if light to be originally entered to a photosensitive element for detecting a luminance component enters into a photosensitive element for detecting a hue component, S/N of signals acquired from the photosensitive element for detecting a hue component is deteriorated and adverse influences given to image qualities are increased.